Applications often require a high voltage DC bus as well as a low DC housekeeping voltage to operate, for example, integrated circuits. It would be desirable to provide a voltage supply circuit that is able to produce a desired DC housekeeping voltage from a high voltage DC bus.
A voltage supply circuit according to the present invention is capable of providing an output DC voltage from and input DC voltage and includes a III-nitride power semiconductor switching device series connected between an input DC voltage bus and an output capacitor.
According to an aspect of the present invention the device is a depletion mode III-nitride power semiconductor device such as GaN-based high electron mobility transistor (HEMT). In one embodiment, the pinch off voltage of a depletion mode III-nitride device in a circuit according to the present invention is used to set the output voltage without a need for complex control circuitry and additional components.
A circuit according to another embodiment further includes a gate controller which is operatively connected to the gate electrode of the III-nitride device. The gate controller may be configured to switch the III-nitride device according to any known switching scheme including preferably pulse width modulation. According to the preferred embodiment of the invention, the gate controller may be a “bang-bang” control that generates a pulse width modulated signal that varies between ground and the desired DC output voltage. By switching the gate of the III-nitride device the output capacitor is charged in a pulse like fashion to the desired DC output voltage. As such, a circuit according to the present invention can be configured to supply any DC output voltage from any DC input voltage.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawing.